Eddy Current Sensor Array for Semiconductor Polishing Endpoint Detection
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Solution Overview
Problem
Existing polishing apparatuses for semiconductor wafers face challenges in accurately detecting the polishing end point, leading to potential short-circuiting due to insufficient polishing and increased resistance or wire removal due to over-polishing, necessitating a more precise method to determine the optimal polishing endpoint.
Innovation Solution
An eddy current detection device with multiple sensors, where the exciting coil and detection coil are integrated within the same core section, and strategically positioned to generate a strong magnetic field, allowing for precise detection of the eddy current formed in the conductive film on the semiconductor wafer, enabling accurate monitoring of the polishing progress and endpoint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single eddy current sensor is used to detect polishing end point, then the device structure is simple, but the detection precision and magnetic field strength are insufficient
Solution Approach 1:
The polishing end point detection system is divided into multiple eddy current sensors (first, second, third, and fourth sensors) positioned at different locations on the polishing table. Each sensor independently detects eddy currents in the conductive film, and their outputs are combined to achieve comprehensive and precise detection across the entire polishing surface, resolving the contradiction between detection precision and device complexity.
Solution Approach 2:
Multiple eddy current sensors are integrated into a unified detection system where their signals are combined through signal processing circuits. This merging of multiple detection points creates a composite detection result that achieves high precision polishing end point detection while maintaining manageable system complexity through modular architecture.
2Measurement precision
If multiple eddy current sensors are deployed to improve detection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The four eddy current sensors are positioned asymmetrically at specific locations on the polishing table (first and second sensors on opposite sides, third and fourth sensors on opposite sides). This asymmetric arrangement optimizes detection coverage and accuracy while maintaining a relatively simple and symmetric overall device structure, balancing precision improvement with complexity management.
3Measurement precision
If the magnetic field strength is increased to improve eddy current detection, then detection sensitivity improves, but energy consumption increases
Solution Approach 1:
The exciting coil generates a concentrated magnetic field localized to the region beneath each eddy current sensor, rather than creating a widespread strong magnetic field across the entire polishing table. This localized field generation achieves high detection sensitivity at each sensor position while minimizing overall energy consumption, as each coil only needs to produce sufficient field strength for its specific detection zone.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides improved accuracy in detecting the polishing end point, preventing short-circuiting and excessive polishing by enhancing the magnetic field strength and detection efficiency, thus ensuring optimal surface flattening of semiconductor wafers.
Implementation Method 1
an exciting coil disposed in the core section and configured to form an eddy current in the conductive film
Implementation Method 2
a detection coil disposed in the core section and configured to detect the eddy current formed in the conductive film
Data Source
AI summary
An eddy current detection device configured to form a stronger magnetic field in a polishing target and a polishing apparatus employing the same eddy current detection device are provided. An eddy current detection device that can be disposed near a semiconductor wafer on which a conductive film is formed includes a plurality of eddy current sensors. The plurality of eddy current sensors are disposed near to one another. Each of the plurality of eddy current sensors includes a pot core, an exciting coil disposed in the pot core and configured to form an eddy current in the conductive film, and a detection coil disposed in the pot core and configured to detect the eddy current formed in the conductive film.